What is this component? It looks a bit like a capacitor, but not exactly, and it is labelled L1 on a small circuit board where there are capacitors labelled C2 and C3…

Mystery Component

  • \$\begingroup\$ As Majenko says, it's a wire wound inductor on a ferrite core (99.99% probability). If you tell us what the circuit is for and/or show us a photo of the wider context we can prbably add more information. \$\endgroup\$
    – Russell McMahon
    Dec 4, 2011 at 21:54
  • \$\begingroup\$ Any other markings, e.g. digits? \$\endgroup\$
    – starblue
    Dec 5, 2011 at 10:03

1 Answer 1


An inductor.

Essentially a coil of wire round a ferrite core.

Here's one without the heatshrink around it:

enter image description here

  • \$\begingroup\$ What is the marking to the right of the "CB" and does the "CB" mean anything? (the manufacturer perhaps?) \$\endgroup\$
    – JonnyBoats
    Dec 4, 2011 at 19:40
  • \$\begingroup\$ It's most likely the markings of the manufacturer of the heat-shrink sleeving the inductor is encased in. \$\endgroup\$
    – Majenko
    Dec 4, 2011 at 19:42
  • \$\begingroup\$ Thanks! Now to go dust off an electronics textbook and try to understand what an inductor does… :-) \$\endgroup\$ Dec 4, 2011 at 20:05

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